Active Ingredients in Sunscreen are Absorbed into the Bloodstream

Active ingredients found in sunscreens are absorbed into the bloodstream at levels that exceed the U.S. Food and Drug Administration’s (FDA) recommended threshold without a government safety inspection, according to a study by the FDA that was published in JAMA.

Researchers assessed the active ingredients (avobenzone, oxybenzone, octocrylene, and ecamsule) of four commercially available sunscreens. This preliminary randomized clinical trial was conducted at a phase I U.S. clinical pharmacology unit and included 24 healthy volunteers (mean age, 35.5 years) between July 2018 and August 2018.

Participants were randomized to one of the four sunscreen options: spray 1 (n=6), spray 2 (n=6), lotion (n=6), and cream (n=6). Participants applied 2 mg of sunscreen per 1 cm2 to 75% of body surface area four times per day for four days (maximal use conditions). Researchers took 30 blood samples over a seven-day period for each participant.

Systemic absorption observed after just one day

Twenty-three participants (96%) completed the trial. Systemic concentrations greater than 0.5 ng/mL were reached for all four products. Under maximal use conditions, plasma concentrations exceeded the threshold established by the FDA for potentially waiving some non-clinical toxicology studies for sunscreens. For all ingredients, the levels of all chemicals far exceeded that limit on the first day of the study, and three of the ingredients remained in the bloodstream for seven days.

For avobenzone, geometric mean maximum plasma concentrations (primary endpoint) were

  • 0 ng/mL (coefficient of variation = 6.9%) for spray 1
  • 4 ng/mL (coefficient of variation = 77.3%) for spray 2
  • 3 ng/mL (coefficient of variation = 46.1%) for lotion
  • 8 ng/mL (coefficient of variation = 32.1%)

For oxybenzone, the corresponding values were 209.6 ng/mL (66.8%) for spray 1, 194.9 ng/mL (52.4%) for spray 2, and 169.3 ng/mL (44.5%) for lotion.

For octocrylene, the corresponding values were 2.9 ng/mL (102%) for spray 1, 7.8 ng/mL (113.3%) for spray 2, 5.7 ng/mL (66.3%) for lotion, and 5.7 ng/mL (47.1%) for cream.

For ecamsule, the corresponding values were 1.5 ng/mL (166.1%) for cream.

The most common adverse event was rash, which was developed by one participant with each sunscreen.

“The systemic absorption of sunscreen ingredients supports the need for further studies to determine the clinical significance of these findings,” the researchers concluded; however, they cautioned, “These results do not indicate that individuals should refrain from the use of sunscreen.”

Source: JAMA; FDA Voices